The field of the invention generally relates to automatic washing machines of the vertical axis or top loading type, and more particularly relates to a filter system for such automatic washing machines.
In the operation of an automatic home washing machine, the agitation and scrubbing of the clothes for removing soil also removes particles of lint and other foreign material from the fabrics. These lint and foreign particles become suspended in the washing fluid and, unless they are removed or filtered therefrom, they may attach to or become deposited back on the clothes being laundered. Accordingly, various types of filters or lint traps have been used in the prior art to remove the lint from the washing fluid.
Many of the prior art filter arrangements include a lint filter centrally positioned within the fabric container or clothes basket such as inside the agitator. These devices ordinarily occupy considerable space within the clothes basket, and reduce the effective access opening into the basket. In addition, a filter of this type normally requires frequent manual cleaning to maintain its effectiveness.
Another prior art approach to lint filtering includes an external recirculating system for removing the washing fluid from the tub and passing it through a filter screen. This type of system, however, includes additional costs for an auxiliary pump, the washing fluid conduits, and the labor to install them.
U.S. Pat. No. 3,352,130 discloses a filtering arrangement in an automatic washing machine wherein the washing fluid is pumped from the outer tub into the clothes basket by the pumping action of the agitator oscillating within the clothes basket during the washing cycle. The washing fluid enters the basket from the tub through openings in the bottom of the basket, and the washing fluid recirculates out through perforations in the sidewall of the basket and down between a space between the tub and the basket. Filter screens are mounted in the openings in the bottom of the basket to collect the lint carried by the washing fluid passing through the openings. The collected lint is then intended to be flushed away during the spin cycle and carried away to the drain. However, the use of a filter screen has a disadvantage in that the ends of fibers may tend to protrude through or become caught on the screen such that the collected fibers are not dislodged by the centrifugal force of the spin mode. Thus, without complete cleaning or flushing during the spin mode, the fibers build on the screen and reduce the recirculation flow rate of washing fluid and the effectiveness of the filter. Eventually, the screen filter may become completely plugged thus eliminating all lint filtering. Also, there is a disadvantage in positioning the filter screens within openings in the clothes basket bottom. Specifically, in order to have enough filter surface area to obtain an acceptable washing fluid flow rate through the filter screens, the openings must be relatively large thus reducing the structural integrity or rigidity the clothes basket. Stated differently, if the structural integrity of the clothes basket is maintained by having relatively small openings for the filter screens, the fluid flow rate may be too small to provide effective filtering. One solution to this problem is to increase the thickness of the basket bottom, but that involves additional costs.
U.S. Pat. No. 4,357,813 discloses another automatic washer filter arrangement wherein the washing fluid is pumped up through openings in the clothes basket bottom by the agitator. Positioned below the clothes basket is a truncated filter cone that has teeth extending upwardly and outwardly from the lower end periphery of the cone. As the pumping agitator draws washing fluid along a path radially inward from the periphery of the tub sump beneath the basket, lint carried by the washing fluid is trapped on and between the teeth of the filter cone. This filter arrangement, however, is relatively inefficient at removing lint as a large percentage of the lint passes between the teeth. Also, lint may tend to be caught on the teeth such that the lint is not washed away during the spin cycle.